Breast cancer is one of the most frequent malignancies worldwide and represents an important public health problem. Despite ongoing improvements in understanding the disease, breast cancer has remained to a large extent resistant to medical intervention. Most clinical initiatives are focused on early diagnosis, followed by conventional forms of intervention, particularly surgery, radiation, hormone suppression, and chemotherapy. Such interventions are of limited success, particularly in patients where the tumour has undergone metastasis. Thus, there is a pressing need to improve the arsenal of diagnostic tools and methods to provide more precise and more effective information that will allow successful treatment in the least invasive way possible. There is also a continuing requirement to identify further and better targets for drug treatment.
In past years, breast cancer has been classified into different subtypes according to molecular parameters. One subtype is characterized by the overexpression of the human epidermal growth factor receptor 2 (HER2), and represents 20%-25% of all breast carcinomas. Separately, it has been demonstrated that CB2 is overexpressed in HER2+ breast cancer, and that CB2 promotes tumor generation and progression by activating HER2 pro-oncogenic signalling via the c-SRC kinase. It has also been shown that CB2 forms heteromers with HER2 in human breast cancer samples.
There is a continuing need to develop better tools for diagnosing, prognosing, and monitoring breast cancer and especially HER2+ breast cancer. It is also important to identify new therapeutic targets.